In the first public account of the incident, the official said the Russian Fencer flew within 1,000 yards of the USS Donald Cook, a Navy destroyer, at about 500 feet above sea level. Ship commanders considered the actions provocative and inconsistent with international agreements, prompting the ship to issue several radio queries and warnings.
The fighter appeared to be unarmed and never was in danger of coming in contact with the ship, said the official, who was not authorized to talk publicly by name about the encounter so spoke on condition of anonymity. The passes, which occurred in the early evening there, ended without incident.
The official also said that a Russian Navy ship, a frigate, has been shadowing the U.S. warship, remaining within visual distance but not close enough to be unsafe.
The USS Donald Cook has been conducting routine operations in international waters east of Romania. The ship, which carries helicopters, was deployed to the Black Sea on April 10, in the wake of the Russian military takeover of Ukraine's Crimea region and ongoing unrest there.
Ukraine's acting President Oleksandr Turchynov on Monday called for the deployment of United Nations peacekeeping troops in the east of the country, where pro-Russian insurgents have occupied buildings in nearly 10 cities. The gunmen are demanding more autonomy from the central government and closer ties with Russia.
The West has accused Moscow of fomenting the unrest. And European Union foreign ministers are meeting in Luxembourg Monday to consider additional sanctions against Russian officials because of Moscow's annexation of Crimea.